MAX809REUR+T Microprocessor Monitoring Circuit for Antminer S19K Pro Control Board

MAX809REUR+T Microprocessor Monitoring Circuit | Power Supply Watchdog for Antminer S19K Pro C76 Control Board

The MAX809REUR+T is a microprocessor supply-voltage monitoring circuit used on the Antminer S19K Pro C76 A113D control board. Accurately monitors +2.5V, +3V, +3.3V, and +5V supply rails, providing precise reset control and protection for the control board's main microprocessor. Requires no external components or adjustments — drop-in replacement when the original fails.

When this chip fails or drifts out of spec, the control board can stay locked in reset state, repeatedly reboot on power-up, or fail to come up cleanly after a brief mains glitch. Common symptom: the control board sits with no LED activity even though all rails measure correctly with a multimeter — the watchdog never releases the microprocessor from reset.

When to Replace the MAX809REUR+T

• Control board stuck in reset — main processor never starts, no boot activity despite healthy rails.
• Repeated reboots on power-up — watchdog tripping early.
• Failure to recover after brief mains glitch — POR pulse not generated correctly.
• Visible damage on the IC package after a fault event.

MAX809REUR+T Specifications

FAQ — MAX809REUR+T Monitor IC

Q: How do I confirm the MAX809REUR+T is the failed part?
A: Measure the RESET pin output with the control board powered on. Healthy chip releases reset (pin goes high) within 140ms of all monitored rails reaching valid levels. Stuck-low reset pin with all rails confirmed healthy on a DMM = monitor chip failed.

Q: Which Antminer models use this exact monitor variant?
A: Confirmed for the S19K Pro C76 A113D control board. Other Antminer models may use the same chip family but different part-number variants (different reset thresholds). Match the silk marking on the failed chip.

Q: Rework profile?
A: Small SOT-23-3 package — hot air at 320°C with flux paste, very short dwell. Easy to overheat the tiny package; preheat the board to 100°C first to reduce thermal shock.

Q: Bulk pricing?
A: Yes — email contact@lys-sz.com for tape-and-reel quantities on MAX809REUR+T stock for S19K Pro control-board repair benches.

Related products

• Antminer S21pro A113D Control Board
• Antminer S21 / T21 Control Board Amlogic A113D Ctrl_C76
• Bitmain CVITEK CV1835 C88 Control Board (KS3 / X5 / S19)
• FM24C02B EEPROM (Antminer S19j Pro+)

S19K Pro control-board repair benches stocking MAX809REUR+T by the reel? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.